Muffler



Oct. 19, 1937. 9 w. c. MILES MUFFLER Original Filed Jan. 25, 1936 2 Sheets-Sheet 1 INVENTOR.

, MUFFLER Original Filed Jan. 25, 1936 2 Sheets-Sheet 2 Patented Oct. 19, 1937 UNITED STATES PATENT OFFICE Application January 25, 1936, Serial No. 60,770 Renewed April 10, 1937 13 Claims.

This invention relates to mufflers for use with internal combustion engines.

An important object of the invention is to provide an improved muffier whichis effective, efficient, simple and inexpensive to manufacture.

Other objects and advantages of the invention will become apparent from the following description when taken in connection with the accompanying drawings, in which- Fig. l is a central, longitudinal, sectional view of a muffler embodying one form of the invenion.

Fig. 2 is an end elevation of the mufller as viewed from the left in Fig. 1.

Fig. 3 is a transverse sectional view taken 'on line 3-3 of Fig. l. v

Fig. 4 is a. transverse sectional view taken on line 44 of Fig. 1.

Fig. 5 is a fragmental, central, longitudinal, sectional view of a slightly modified form of muffler.

Fig. 6 is a transverse, sectional view taken on line 66 of Fig. 5.

Fig. 7 is a fragmental View showing in elevation a modified form of equalizing tube that may be employed in lieu of the respective equalizing tubes of Figs. 1 and 5.

Fig. 8 is a transverse sectional view taken on line 88 of Fig. 7.

Fig. 9 is a longitudinal, sectional view taken on line 9-9 of Fig. '7.

Fig. 10 is a fragmental view similar to that of either Fig. 1 or Fig. 2, and showing, in a muffler from which certain elements are omitted, an optional arrangement of divisional walls forming transverse chambers of different lengths, and

Fig. 11 is an end view of a modified form of deflector tube.

Referring particularly to Figs. 1 to 4, the numeral 40 indicates a sheet-metal shell or casing which is elliptical or substantially elliptical in transverse section, as shown most clearly in Figs. 3 and 4, and to opposite ends of which are suitably connected, as by lock seaming, a pair of sheet-metal heads H and I2.

receiving openings 14 and [5, the former of which is adapted to receive a coupling flange or tube I6 by'which the muffler may be conveniently connected to the exhaust pipe, not shown, of an internal combustion engine, and the latter of which is adapted to receive an outlet tube ll through which exhaust gases may escape from the mufller directly into the atmosphere or by which such gases may be directed into a tail pipe, not shown, of the typeoften employed for leading the ex- The heads It and 12 are provided, respectively, with flanged tubehaust gases from the outlet end of the muffler to a point relatively remote therefrom.

Disposed within the muffler casing i0 is an equalizing unit l8 which functions to direct the exhaust gases through the rruifler in such a manner that exhaust noises are eliminated to a very marked degree without substantially detracting from the normal efliciency of the engine under any and all operating conditions.

The above-mentioned equalizing unit [8 is constructed wholly of sheet metal and includes a pair of tube-forming walls a-a which are identical and which form with each other an equalizing tube and a pair of feeder tubes 2| and 22, the tube 20 being provided at opposite sides, as shown most clearly in Fig. 4, with a longitudinal series of slot-like ports 24 adjacent to each of which is disposed a deflecting lip 25 and the tubes 2| and 22 being respectively provided at one side thereof with a longitudinal series of slot-like ports 26 and 20 21 adjacent to which are disposed deflecting lips 28 and 30. It is to be observed that when the tube-forming walls a-a, each of which is in the form of a corrugated sheet of metal, are placed in a contiguous or tube-forming relation, they 25 may be readily secured in that relation by spotwelding or otherwise joining their complementary webs bb and their complementary flanges c-c to each other, the webs b--b of each wall being disposed between the intermediate corrugation 30 and the marginal corrugations thereof and the flanges c-c of each wall being disposed at the outer longitudinal edges of the marginal corrugations of such wall. As to the slot-like ports 24, 26 and 21, they may be readily formed by shearing the metal of the tube-forming walls aa at deflnitely located intervals and depressing or distorting the lip-forming portions of the metal adjacent such points of shearing, the desired width and inclination, respectively, of the slot-like ports and deflecting lips thus formed being easily attainable by suitably constructed metal working dies. 1

Associated with the equalizing tube 20 and the feeder tubes 2| and 22, are a pair of end walls 3| which are identical and form with the muffler heads I I and I2, respectively, an inlet chamber E and an outlet chamber F. Each of these end walls is provided with a peripheral flange 32 which is adapted to snugly fit the inner wall of .the muffler casing l0 and is formed with flanged openings 34, 35 and 36 adapted to receive, and within which snugly flt, opposite ends of the respective tubes 20, 2|, and 22. As will be understood from an inspection of Fig. 1, the opposite ends of the tubes 20, 2|, and 22 are adapted to accommodate the end walls 3| inasmuch as the webs b-band the flanges 0-0 of the tube-forming walls a-a. are cut away to an extent equal to the thickness ,of the metal from which the end walls are formed plus the length of the respective flanges 31 which project .outwardly from the end walls in the vicinity of their tube-receiving openings 34, 35, and 36.

Located intermediate the end walls 3| are a plurality-of divisional walls 38fwhich are disposed transversely of the mufller casing II] at points intermediate the respective groups of ports 24, 26, and 21, and thus divide the mufiier, intermediate the end walls 3|, into a plurality of transverse chambers (1. Each of the divisional walls 38 is provided with a peripheral flange 40, is adapted to snugly fit the inner wall 32 of the casing l0 and is 7 formed with a pair of slots GI and with a pair of notches 42 adapted to accommodate and snugly fit the webs b*-b and the flanges cc of the tube-forming walls aa.

It will be understood that the end walls 3| and the divisional walls 38 may be held in their respective positions shown in Fig. 1 by welding them, at suitable locations, to one or both of the tube-forming walls aa prior to inserting the equalizing unit in the casing I0 and that such unit may be held in a definite position within the muflier casing ID by welding such casing to the flanges 32 and 40, respectively, of the end walls 3| and the divisional walls 38.

Although highly satisfactory results have been obtained in tests made on the present mufiler with'the feeder tubes 2| and 22 open at both ends, and also with those tubes opened at the inlet end of the mufiler and closed at the outlet end there- 'of, the most satisfactory results were obtained on tests which were made when one of the tubes fl-22 was closed at the inlet end of the muffler and both of such tubes were open at the outlet end of the muiiier. It is preferred, therefore, to so construct the mufller that one of the tubes 2l-22 is closed at the inlet end of the muffler, and with that in view a suitable closure is illustrated consisting of a cup-like member 44 which may be securedjas by welding, within the tube 22 as shown in Fig. l. a

Secured within the equalizing tube 20, as by welding, is one end of an outwardly flared connector sleeve 45, having at its outer end a cylindrical flange 46 which is adapted to receive thereon andto be welded to a'deflector tube 41, the inlet end of which is such that it snugly fits within the coupling flange |6. As will be understood from Figs. 1 and 2, the deflector tube 41 is so formed, by pressing portions of its wall inwardly toward the axis of the tube, as to present a cenduplicate tube-forming walls 11-0., and that the tral throat-like passage 48 which is in direct alignment with the axis of the coupling tube I6 and the axis of the equalizing tube 20, the passage 48 being of uniform area throughout such length of the tube 41 as is confined within the coupling flange I6, and gradually increasing in area toward its point of connection with the connector sleeve 45. It will be appreciated from Figs. 1 and 2 that the tube 41, by reason of its particular shape, forms with the coupling flange or tube I6 a pair of passages 50 which afford direct communication between that tube and the inlet chamber E of the mufiier and that the central passage 48 affords a direct communication between the coupling tube and the equalizing tube 20, within the outer end of which latter tube the inner end of-the outlet tube I1 is secured, as by welding.

1, it will be noted that the equalizing tube 20 is provided with a pair of slot-like ports 52 and that the feeder tubes 2| and 22 are, respectively, provided with single slot-like ports 5| and 53. Inasmuch as these ports extend throughout the major portion of the length of the equalizing unit I8 and are, respectively, the same width as the corresponding ports 24, 26, and 21, it follows that the equalizing unit may be shorter than the equalizing unit l8 and that the length of the modified mufller may be correspondingly less than the mufller of Fig. 1, although the port-areas of the equalizing tubes 20 and 20' may be the same, as is also true of' the port-areas of the feeder tubes 2|2|' and 22 22'.

Referring to Figs. 7 to 9, wherein is, shown a modified form of equalizing tube 20", it will be understood that the equalizing tube 20 of the equalizing unit |8 (Fig. l) or the equalizing tube 20' of the equalizing unit l8 (Fig. 5) may be so fabricated as to provide, instead of the ports 24 and 24', a series of slot-like ports 24" by shearing the tube-forming walls d"a" at spaced locations along a helical path and by depressing or distorting the metal adjacent such points of shearing to provide deflecting lips 25" which extend generally both longitudinally and transversely of the equalizing tube.

From Fig. 10, it will become apparent that the mufiiers-hereinbefore described lend themselves to a further modification, insofar asthe lengths of the transverse chambers 63 (Fig. l) and d (Fig. 5) are concerned. If it is desired to provide transverse chambers having, for example, lengths varying in the order or ratio of one, two and four, when considered in a sequence beginning at one end of the mufiler, divisional walls, such as those indicated by the numerals 38 and 38' in Figs. 1 and 5 and identified in Fig. 10 by the numeral 38" may be positioned within the muiiler casing l0" according to the arrangement illustrated.

Taking into account the structural characteristics of the various elements entering into the present invention and the fact that such elements are of sheet metal, it becomes apparent that they admirably lend themselves to economical quantity production. In this connection it is to be particularly noted, for example, that the connector sleeve 45 may be readily produced by a simple die operation, that the deflector tube 41 may be likewise produced, that but a single die is required for producing the duplicate end walls 3| may be formed in a single die, as is also true of the divisional walls 38. Aside from the fact that the various elements entering into the present invention admirably lend themselves to economical quantity production, it is to be further observed that they are also such that they may be easily and expeditiously assembled.

Although it is believed that the present in vention may be readily constructed by one skilled in the art in view of the foregoing description, it might be well to here set forth certain of the dimensions employed in connection with a mufller constructed in accordance with the disclosures of Fig.1 and subjectedto decibel meter and dynamometer tests which were conducted,

with highly satisfactory results, in connection with a six-cylinder Chevrolet internal combustion engine. 'I'he dimensions were as follows: Casing Ill-19%" long, 3 on its Y-Y axis, and 5%" on its 2QX axis; equalizing unit l816" long; inside diameter of equalizing tube 20--1 inside diameter of feeder tubes 21 and 22-each 1%; passage-areas of feeder tubes 2| and 22-each 1.223 square inch; equalizing tube ports 24 (5 located at opposite sides of the equalizing tube 20 and spaced from each other 1").each 2" long, 1/20" wide, and having an area of .1 square inch; feeder tube ports 26 and 21 (5 to a tube and spaced 1" apart) each 2" long, wide, and having an area of .125 square inch; inside dimension of coupling tube Iii-1%"; area of inlet end of deflector tube 41--approximately .851 square inch; outside dimension of deflector tube 41-1%" outside diameter of outlet tube |1-1%; gauge of metal--casing ll) of U. S. Standard No. 18, outlet tube l1, connector sleeve 45, deflector tube 41, and equalizing-unittube-forming walls w-a of U. S. Standard No. 22.

After testing the above dimensionally identified mutller, further tests were carried out with that muliler to determine what effect, if any, might be obtained by reducing the inlet area of thedeflector tube 41. Such inlet-area-reduction was effected by partially blocking the inlet end of the deflector tube by means of plugs of different sizes, so as to obtain inlet areas of approximately .6, .4, and .3 square inch, respectively. During these further tests, it was observed that as the inlet area was decreased the muflling ability was improved at the expense of aslight increase in back pressure, the increased back pressure being accounted for by the fact that the areas of the feeder tubes 2|, 22 and slot-like ports 24, 26, and 21 were not increased in accordance with the decrease in inlet area of the deflector tube but were retained at their respective values above mentioned. After taking into account the factor of back pressure as against mufliing effect, or vice-versa, an inlet area of approximately .4 square inch was selected as. best suited to the above dimensionally identified mufiler.

Should it be desired, in commercial manufacture of mufflers embodying the presentinvention, to restrict the area of the inlet end of the deflector tube to an extent substantially greater than that which is suggested in Fig. 2 and which is in the order of approximately .851 (area, in terms of square inches, of the inlet end of the deflector tube 41) 2.5802 (area, in terms of square inches, of passage of tube-forming member from which deflector tube 41 is fabricated), such restrictions can best be obtained by shaping the inlet end of the deflector tube in accordance with the disclosure of Fig. 11, wherein is shown a modified form of deflector tube 41" which is identical with, for example, the deflector tube'41, except that its wall is pressed inwardly at three difi'erentlocations, the metal available in the wall of the tube member from which the deflector tube is fabricated being ample to permit any desired extent of closing of the inlet end of the tube member to be attained without displacing such of the wall-metal as enters into the formation of the peaks 41a which are produced incident to the tube-fabricating operation and are adapted to snugly fit within, for example, the coupling tube or sleeve 16 of Fig. 1.

Operation In view of the fact that any attempt to here ports 24.

describe the operation of the invention from a purely technical standpoint might possibly lend to confusion, and since such technical explanation is not here required, it will sufllce to trace the paths which the exhaust traverses in passing through the mufller and to comment on the same wherever necessary for the sake of clarity.

Referring to Fig. 1, it will appear that when the coupling tube I6 of the muflier is attached to the exhaust pipe, not shown, of an internal combustion engine and such engine is operated at'various speeds under'its own power, a portion of the exhaust emitted from the engine will pass directly into the equalizing tube 20 by way of the throatlike passage 48 of the deflector tube 41, and another portion of such exhaust will enter the equalizing tube by way of the passages 50, the inlet chamber E, the feeder tube 2 l the feeder tubeports 26, the outlet chamber F, the feeder tube 22, the feeder tube ports 21, and the equalizing tube ports 24. Such exhaust as escapes from the feeder tubes 2| and 22 by way of their respective ports 26 and 21 will be whirled around the equalizing unit l8 in the direction indicated by the arrows g of Fig. 4, the whirl being common to the respective chambers d, each of which is common to a pair of the feeder tube ports 26 and 21 and a pair of the equalizing tube ports 24. It will be noted that the whirling exhaust within the respective chambers d undergoes an abrupt change in its direction of travel with respect to the X-X axis, or rather with respect to the plane of the X-X axis, of the elliptical or substantially elliptical casing ID at points where it passes from one side of such X-X plane to the other side thereof. It is the inner portion, at a given instant, of the exhaust in the surrounding vicinity of the equalizing tube 20 that enters that tube by way of its The exhaust thus entering the equalizing tube 20 impinges on the deflector lips 25 and is thereby caused to undergo a whirling action within that tube. Within the equalizing tube 20, the whirling exhaust traverses a helical path as it travels along with and commingles with the exhaust entering that tube by way of the throatlike passage 48 of the deflector tube 41.

In view of the similarity between the mufllers of Figs. 1 and 5, it is believed that no description of the operation of the mufiler of the latter figure is here necessary. Moreover, it is believed that no detailed description of theoperation of the equalizing tube 20" (Figs. '1 to 9) is here deemed necessary other than to point out that if such tube is employed in connection with either the mufiler of Fig. 1 or the muiller of Fig. 5, the exhaust entering that tube by way of the equalizing tube ports 24" will be directed by the deflector lips 25" in a helical path along which it is whirled as it passes through and is expelled from 2 Additionally, it is believed that no the muffler. comments, from an acoustical or other standpoint, are necessary with respect to the optional divisicnal-wall-arrangement illustrated in Fig. 10.

Aside from the modifications either herein shown and described, or suggested, it will be understood that various other changes, such, for example, as the elimination of transverse walls (38, 3B, 38"), or, for example, the use of a cylindrical casing in lieu of the elliptical or substantially elliptical casing Ill, may be resorted to without departing from the spirit of the invention.

What is claimed is:

1. In a muflier, means for dividing a column of exhaust, on equalizing tube having a ported side-- wall area and adapted to convey one portion of 15 the divided exhaust. a feeder tube having a ported side-wall area and adapted to convey a second portion of the divided exhaust, and a reservoir communicating with said tubes by way of their ported wall areas and adapted to receive exhaust from said feeder tube by way of its ported wall area and to deliver such exhaust to said equalizing tube by way of its ported wall area, said reservoir including a casing surrounding said tubes and so disposed with respect to theported wall area of said feeder tube as to direct exhaust, issuing from that tube in a whirl-path. 4

2. In a muflier, means for dividing a column of exhaust, an equalizing tube having a ported sidewall area' and adapted to convey one portion of the divided exhaust, a feeder tube having a ported side-wall area and adapted to convey a second portion of the divided exhaust, a reservoir communicating with said tubes by way of their ported wall areas and adapted to receive exhaust from said feeder tube by way of its ported wall area and to deliver such exhaust to said equalizing tube by way of its ported wall area, said reservoir including a casing surrounding said tubes and so disposed with respect to the ported wall area of said feeder tube as to direct exhaust issuing from that tube in a whirl-path, and deflector means associated with the ported wall area of said equalizing tube for so directing exhaust passing into that tube by way of its ported wall area as to impart a whirling action to itself and to said one portion of the divided exhaust.

3. In a muflier, means for dividing a column of exhaust, an equalizing tube having a ported sidewall area and adapted to convey one portion of the divided exhaust, a feeder tube having a ported side-wall area and adapted to convey a second portion of the divided exhaust, a reservoir communicating with said tubes by way of their ported wall areas and adapted to receive exhaust fromsaid feeder tube by way of its ported wall area and to deliver such exhaust to said equalizing tube by way of its ported wall area, said reservoir including a casing surrounding said tubes, and deflector means associated with the ported wall area of said feeder tube and serving in conjunction with said casing to direct exhaust issuing from that tube in a whirl-path.

4. In a muffler, means for dividing a column of exhaust, an equalizing tube having a ported sidewall area and adapted to convey one portion of the divided exhaust, a feeder tube having a ported side-wall area and adapted to convey a second portion of the divided exhaust, a reservoir communicating with said tubes by way of their ported wall areas and adapted to receive exhaust from said feeder tube by way of its ported wall area and to deliversuch exhaust to said equalizing tube by way of its ported wall area, said reservoir including a casing surrounding said tubes, deflector means associated with the ported wall area of said feeder tube and serving in conjunction with said casing to direct exhaust issuing from that tube in a whirl-path, and deflector means associated with the ported wall area of said equalizingtube for so directing exhaust passing into that tube by way of its ported wall area as to impart a whirling action to itself and to said one portion of the divided exhaust.

5. In a muiiier, means for dividing a column of exhaust into portions respectively subordinately and preponderantly proportioned with relation to each other, an equalizing tube having a ported side-wall area and adapted to convey the subordinate portion ofthe divided exhaust, a feeder a ported side-wall area, and a reservoir communicating with said tubes by way of their ported wall areas and adapted to receive exhaust from said feeder tube by way of its ported wall area and to deliver such exhaust to said equalizing tube by way of its ported wall area, said reservoir including a casing surrounding said tubes in a spaced relation thereto and so disposed with respect to the ported wall area of said feeder tube as to direct exhaust issuing from that tube in a whirl-path of which the spaces intermediate said casing and said tubes form parts.

6. In a muilier, means for dividing a column of exhaust into portions respectively subordinately and preponderantly proportioned with relation to each other, an equalizing tube having a ported side-wall area and adapted to convey the subordinate portion of the divided exhaust, a feeder tube disposed'contiguously to said equalizing tube and adapted to convey the preponderant portion of the divided exhaust, said feeder tube having a ported side-wall area, a reservoir communicating with said tubes by way of their ported wall areas and adapted to receive exhaust from said feeder tube by way of its ported wall area and to deliver such exhaust to said equalizing tube by way of its ported wall area, said reservoir including a casing surrounding said tubes in a spaced relation thereto and so disposed with respect to the ported wall area of said feeder tube as to direct exhaust issuing from that tube in a whirl-path of which the spaces intermediate said casing and said tubes form parts, and deflector means associated with the ported wall area of said equalizing tube for so directing exhaust passing into that tube by way of its ported wall area as to impart a whirling action to itself and said subordinate portion of the divided exhaust.

'7. In a muiiler, an elliptical-like casing serving as a reservoir, means for conveying exhaust through said casing and for so directing such exhaust against the inner wall of said casing as to cause it to whirl about the axis of such casing, and means for guiding the whirling exhaust in a path corresponding substantially to the elliptical contour of said casing.

8. In a muiller; a reservoir; means for dividing a column of exhaust; an equalizing unit comprising a pair of tube-forming walls disposed in a contiguous relation and shaped to form with each other an equalizing tube having a ported area and adapted to receive one portion of the divided exhaust and a feeder tube having a ported area and adapted to receive a second portion of the divided exhaust, said ported areas and said reservoir affording a path of communication between said feeder tube and said equalizing tube whereby said second portion of the divided exhaust is transmitted to said equalizing tube by way of the ported area thereof.

9. In a muiiler; a reservoir; means for dividing a column of exhaust; an equalizing unit comprising a pair of tube-forming walls disposed in a contiguous relation and shaped to form with each other an equalizing tube having a ported area and adapted to receive one portion of the divided exhaust and a feeder tube having a ported area and adapted to receive a second portion of the divided exhaust, said ported areas and said reservoir affording a path of communication between said feeder tube and said equalizing tube whereby said second portion of the divided exhaust is transmitted to said equalizing tube by way of the ported area thereof, and deflector means associated with the ported area of said feeder tube for so directing exhaust passing from that tube by way of its ported area as to impart to itself a whirling action within said reservoir.

10. In a muilier; a reservoir; means for dividing a column of exhaust; an equalizing unit comprising a pair of tube-forming walls disposed in a contiguous relation and shaped to form with each other an equalizing tube having a ported area and adapted to receive one portion of the divided exhaust and a feeder tube having a ported area and adapted toreceive a second portion of the divided exhaust, said ported areas and said reservoir affording a path of communication between said feeder tube and said equalizing tube whereby said second portion of the divided exhaust is transmitted to said equalizing tube by way of the ported area thereof, and deflector means associated with the ported area of said equalizing tube for so directing exhaust passing into that tube by way of its ported area as to impart a whirling action to itself and to said one portion of divided exhaust.

11. In a muffler; a reservoir; means for dividing a column of exhaust; an equalizing unit comprising a pair of tube-forming walls disposed in a contiguous relation and shaped to form with each other an equalizing tube having a ported area and adapted to receive one portion of the divided exhaust and a feeder tube having a ported area and adapted to receive a. second portion of the divided exhaust, said ported areas and said reservoir affording a path of communication between said feeder tube and said equalizing tube whereby said second portion of the divided exhaust is transmitted to said equalizing tube by way of the ported area thereof, deflector means associated with the ported area of said feeder tube for so directing exhaust passing from that tube by way of its ported area as to impart to itself a whirling action within said reservoir, and deflector means associated with the ported area of said equalizing tube for so directing exhaust passing into that tube by way of its ported area as to impart a whirling action to itself and to said one portion of divided exhaust.

12. In a muflier; a reservoir; means for didividing a column of exhaust; an equalizing unit arranged within said reservoir and spaced from the inner wall thereof to afford circulatory communication between adjacent sections of the reservoir and comprising a pair of tube-forming walls disposed in a contiguous relation and shaped to form with each other an equalizing tube having a ported area and adapted to receive one portion of the divided exhaust and a feeder tube having a ported area and adapted to receive a second portion of the divided exhaust, said ported areas and said reservoir affording a path of communication between said feeder tube and said equalizing tube whereby said second portion of the divided exhaust is transmitted to said'equalizing tube by way of the ported area thereof, and deflector means associated with the ported area of said feeder tube for so directing exhaust passing from such tube by way of its ported area as to cause it to whirl itself about the equalizing unit prior to its entering said equalizing tube.

13. In a muffler; a reservoir; means for dividing a column of exhaust; an equalizing unit arranged within said reservoir and spaced from the inner wall thereof to afford circulatory communication between adjacent sections of the reservoir and comprising a pair of tube-forming walls disposed in a contiguous relation and shaped to form with each other an equalizing tube having a ported area and adapted to receive one portion of the divided exhaust and a feeder tube having a ported area and adapted to receive a second portion of the divided exhaust, said ported areas and said reservoir affording a path of communication between said feeder tube and said equalizing tube whereby said second portion of the divided exhaust is transmitted to said equalizing tube by way of the ported area thereof, deflector means associated with the ported area of said'feeder tube for so directing exhaust passing from such tube by way of its ported area as to cause it to whirl itself about the equalizing unit prior to its entering said equalizing tube, and deflector means associated with the ported area of said equalizing tube for so directing exhaust passing into that tube by way of its ported area as to impart a whirling action to itself and to said one portion of divided exhaust.

WILLIAM C. MILES. 

